Apparatus and method of fuel burning



Oct. 1, 1929.

L. DE FLOREZ APPARATUS AND METHOD OF FUEL BURNING Filed Nov. 2, 1925 2Sheets-Sheet 1 awuemtoz a 7"2 III/ll w w w Oct. 1, 1929. L. DE FLOREZAPPARATUS AND METHOD OF FUEL BURNING 2 Sheets-Sheet 2 avwemtoz FiledNov. 2, 1925 a? HIM/n Patented Oct. 1, 1929 UNITED [STATES PATENT OFFICE121718 on now, or won-am, eounne'rrcu'r, Assmuon To run" 'rnxns aconromrrou or nnmwmn nrm'rus am) Eamon or rum. BUENING.

Application fled November 2, 1925. Serial No. 68,335.

This invention relates to improvements in the art of burning fuel in afurnace and articularly in a furnace of the type in w 'ch the fuel is suplied by a jet.

It is well inown that for the maximum economy fuel should be burned withjust sufficient air for proper combustion, but in practice it is oftenfound that burning fuel under such conditions creates 'fire boxtemperatures which are too high for practical operation inasmuch as theycause a rapid deterioration of brick settings and the heating elements.

In order to permit the combustion of the fuel under the most efiicientconditions, and

5 at the same time reduce the fire box temperature to a practicalmaximum and to attain other advantages, such as increasing the velocityof the heated gases by the heating surfaces to efliect a greatertransfer of heat, it

has been the practice to introduce a portion of the spent products ofcombustion or flue gases, either from the furnace itself, or from othersuitable sources, whereby the tempera ture of combustion is moderatedand it is thus made possible to control to some ditions resulting inrapid deterioration and consequently high cost of maintenance.

The object of my invention is to accomphsh the introduction, byutilizing the energy of a jet such as that formed by the fuel burner,irrespective of theparticular form of burner used, of gases extraneousto the jet such as flue gases or other suitable dilutmg medium into thefire box of the furnace.

For instance, the invention is applicable where a fuel oil burner of thesteam atomizing type, either with or without forced draft, is used, orwhere a gas burner with or without a steam jet and forced draft is used,or

where a powdered fuel burner in which the powdered fuel is served to theburner by a streem of alror other suitable vehicle is use The jet ofincandescent gases injected into the furnace 1s composed of fuel, airand in some lnstances steam, all of which or part of which may besupplied to the burner under pressure. Irrespective of the particulartype of burner used in the application of my inventlon, the; energyavailable to aspirate the flue gases from a suitable source and injectthem 1nto the furnace is derived from the initial pressure under whichthe various elements required for combustion or to assist combustion arefed to the burner, and also to the velocity head generated by theexpansion of the gases and vapors incident to combustion which velocityhead is used to overcome the dlifere'nce in pressure between the sourceof supply of the flue gases and that existing in the fire box. v

For the purpose of simplifying the disclosure of the invention I willrefer to the various combinations of elements discharged from theburners of whatever type they may be into the combustion chamber as theoutput of the burners. I will, however, for the pur pose oflllustration,describe the application of the invention to the various types ofburners to which I have hereinbefore r -ferred.

In the drawings: v Figure 1 is a vertical sectional view ofa furnace inwhich tubular heating elements are employed, the burner in this instancebeing of the steam atomizing type,

Figure 2 is a similar-view showing the apllcation of the invention wherefuel oil is injected without the use of steam to produce combustion inthe fire box of a furnace used in connection with a shell still; and

Figure 3 is a fragmental sectional view 7 showing the application of-theinvention to a owdered coal burner.

eferring now particularly to the construetion shown in Figure 1, thefurnace includes a fire box 1, having the usual bridge wall 2 and'flue3, which leads to a stack 4, the heating elements 5 being arranged inthe path of the products of combustion as they pass from the fire box tothe flue.

The burner here illustrated includes an outer tube 6 which is madepreferably of heat resisting-material, has an 0 en end 7 and variableair. inlet ports 8 t e tube being mounted in a housing 9. ounted withinthe outer tube 6 is a steam tube 10, opening toward the open end 7 ofthe outer tube 6 and receiving its steam from a source of supply througha steam inlet 11. A11 011 supply tube 12 is arranged within the steamtube 10 and opens toward the end of the same, terminating preferablyshort of the open end of the steam tube.

If desired, the air inlet ports 8 may be supplied with air under ressurefrom a suitable source,such as a b ower 13- The burner extends into achamber 14 in the housing 9 which chamber is preferably in the form of aVenturi tube opening into the combustion chamber of the furnace. The

1 open endof the outer tube 6 which tube extends beyond the steam tube10, is located preferab y at the throat of the Venturi tube.

Communication is established between the chamber 14 and the flue 3 bymeans of a duct 15, the flue 3 being provided with a baflle 16 adjacentthe duct. This duct 15 communicates with the chamber 14 at a pointpreferably to the rear-of the open end of the tube 6, and is providedwith a damper 16 by means of which the effective area of the duct may bevaried.

The combustion chamber of the furnace may also be provided with an airinlet opening 17 having a damper 18 therein, for controlling theeffective area of the duct.

In operation the elfect of the jet-caused by the burner is to create areduced pressure in the rear of the chamber 14 and draw a portion of theflue gases therein from the duct 3. These flue gases are then forcedinto the fire box of the furnace by the jet.

The magnitude of the jet will be dependent upon the amount of fuelburned, since the air requirements and steam requirements will besubstantially regulated for good combustion in accordance with theamount of fuel handled, and the quantity of flue gases will also besubstantially proportional to the amount of fuel burned. Consequentlyfor a given opening of the damper 16' a substantially constantproportion of flue gaseswill be admitted to the furnace, the proportion,however, bearing a definite relation to the output of the burner andvarying with the output of the burner. The variation of the area of theduct 15 varies the ratio of the flue gases to the output of the burner.

The auxiliary air port 17 which is controlled by the damper 18 may beused should it be found desirable to operate the burner with aninsufliciency of air, the desired auxiliary air being adniitted throughthis port.

The construction. illustrated in Figure 2 includes a furnace having afire box 19, a

bridge wall 20, and a flue'21, leading to a stack 22. A shell still 23is supported above the fire box of the furnace. In this form the tube 24having an open inner end 25 ismounted in a housing 26 and is providedwith variable air inlet orts 27 whlch may or may not be supplied withair under pressure. An oil injection tube 28 extends into the tube 24and terminates short of the open end of this tube. The housing 26 isprovided with a chamber 29 in which the burner is located, whichchamberopens into the fire box of the furnace and as illustrated ispreferably cylindrical in form, communication being established betweenthe chamber and the flue 21 by a duct 30 having a control damper 31therein for varying the effective area of the duct, there being provideda bailie 32 adjacent the duct which extends into the flue 21. In thisform of the invention, where the oil is fed through the pipe 28 underpressure without the use of steam, the resultant et caused by the burnercreates a reduced pressure in the rear of the chamber 29 and draws aportion of the flue gases therein through the duct 30, which flue gasesare then forced into the fire box by the et.

When a powdered coal burner such as illustrated in Figure 3 is used, theoperation of injecting the portion of the flue gases into the firebox ofthe furnace is substantially the same. This burner includes a tube 33having an open end 34, opening into a chamber 35 of the housing 36, andhaving variable air inlet ports 37 which may either be supplied with airunder atmospheric or superatmospheric pressure. The powdered coalinjector 38 which is connected to a suitable pressure source 39 extendsinto the tube 33 and discharges therein at a point to the rear of theopen end of the tube. The chamber 35' has communication with the flue ofthe furnace through a duct 40 having a control damper 41 therein whichduct preferably communicates with the chamber 35 to the rear of the openend of the tube 34.

Of course when a gas burner is used the action of the jet in injectingthe extraneous I gases into the furnace is similar to that when theother types of burners are used.

I have illustrated three types of burners and have illustrated thechambers into which the burners extend in the forms of cylinders and aVenturi tube, but it is to be understood that either the cylindricalform or the Venturi tube form may be used with any of the burners, andfurthermore, that the burners may be so disposed as to dischargedirectly into the fire box of the furnace, communication beingestablished with the flue so that the pressure created by the jet willdraw the requisite amount of flue gases from the flue and inject theminto the fire box.

I do not wish to be limited to the particular embodiment of theinvention which I have shown, for it is obvious that many details ofconstruction of the apparatus may be made without departing from thescope of the claims.

WVhat I claim is:

1. In the heating of a furnace, the method of effecting a recirculationof a portion of the flue gases which comprises passing a jet of burningfuel and the products of combustion thereof into the furnace, permittinga predetermined expansion of the gaseous combustion products andutilizing the kinetic energy of such expansion to draw flue gases intothe furnace, thereby maintaining the temperature of the furnacerelatively low.

2. The method of heating a furnace chamber which comprises injectingthereinto a jet of fuel, forming a high temperature flame by supplyingsubstantially the amount of air required for complete combustion of saidfuel, permitting the flame and the gaseous products of combustion toexpand, thereby creating kinetic energy, and employing such energy toeffect the introduction of hot flue ases to mix with the combustionproducts, W ereby the temperature of the furnace chamber is keptrelatively low by such admixture.

3. In the heating of a furnace, the method of effecting a recirculationof a portion of the flue gases which comprises passing a jet of burningfuel and the products of combustion thereof into the furnace, permittinga predetermined expansion of the gaseous combustion products, utilizingthe kinetic energy of i such expansion to draw flue gases into thefurnace, and regulating the quantity of flue gases so recirculated toprovide the desired temperature conditions in the furnace.

4. In a furnace, in combination, a fire box,

a fuel burner projecting into said fire box,

means for supplying fuel and air to the burner, said burner beingadapted to produce a norm ally developed high temperature flame, a fluefor leading away Waste gases from the fire box, a fire resisting passagesurroundin said burner and extending therebeyond an spaced therefrom asuflicient distance to permit substantial expansion of the flame and thehot products of combustion while in said passage, and a conduit meansconnecting said flue with said passage and enabling the drawing in of aportion of said waste gases by the expansion of the hot combustiongases.

5. In a furnace, in combination, a fire box, a fuel burner projectinginto said fire box, means for supplying fuel and air to the burner, saidburner bein adapted to produce a normally developed igh temperatureflame, a flue for leading away waste gases from the fire box, a fireresisting Venturi tube surrounding said burner and extending therebeyondand spaced therefrom a suflicient distance to permit substantialexpansion of the flame and the hot products of combustion while in saidVenturi tube, a conduit means rounding said burner and extendingtherebeyond and spaced therefrom a suflicient dis tance to permitsubstantial expansion of the flame and the hot products of combustionwhile in said Venturi tube, a conduit means connecting said flue withsaid Venturi tube and enabling the drawing in of a portion of said Wastegases by the expansion of the hot combustion gases, and means located insaid conduit means for controlling the flow of waste gases therethrough.

In testimony whereof, I have signed my name to this specification this30th day of October, 1925i LUIS DE FLOREZ.

